Charlotte and her brother, Jacob, are thrilled to head off on an adventure in their grandpa's boat, The Seawind. As they set sail for Pirate Island, they look forward to a day of beachcombing, playing pirates and storytelling. There are plenty of great treasures to be found, but Charlotte, who can be very bossy, is having trouble sharing with Jacob. When Charlotte accidentally loses one of Jacob's best finds, a piece of driftwood that looks just like a pirate's cutlass, it's the final straw. Feeling horrible for upsetting her brother, Charlotte is determined to set things right.